All good points. For what it's worth, I was once departing out of Hong Kong, we were heavy, and needed about 265 to clean up. We asked for "high speed climb" and they replied with "speed restrictions removed, speed at your discretion." It seems there's really no cut and dry answer. I know in HKG they want you to speed up as fast as possible and get out of their airspace, so we usually hear no grief from them about doing 300+ by 6000'. I guess the right answer would be to play it safe, and ask for approval regardless of what they tell you.